[petsc-users] periodic boundary conditions

[Matthew Knepley]

On Tue, Jul 18, 2023 at 9:02 AM Karthikeyan Chockalingam - STFC UKRI via
petsc-users <petsc-users at mcs.anl.gov> wrote:

> Hello,
>
>
>
> This is exactly not a PETSc question. I am solving a Poisson equation
> using finite elements. I would like to impose PBC. I am thinking of using
> the Lagrange multiplier method to impose them as constraints. Or do you
> think I could take an alternative approach?
>

There are several options:

1) Just make a periodic mesh. This is what Plex does by default.

2) Impose the conditions strongly. This is what is done if you create the
ZBox shape in Plex.

3) Impose the conditions weakly. This is what you are doing with Lagrange
multipliers. You could
also do a Nitsche boundary condition for this.

Since the constraint is so simple, I do not see an advantage to imposing it
weakly.

  Thanks,

     Matt


> Thank you for your help.
>
>
>
> Kind regards,
>
> Karthik.
>
>
>
> --
>
> *Dr. Karthik Chockalingam*
>
> High Performance Software Engineering Group
>
> Hartree Centre | Science and Technology Facilities Council
>
> karthikeyan.chockalingam at stfc.ac.uk
>
>
>
>  [image: signature_3970890138]
>
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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